• Club are the most valuable sports team in the world• Share price driven up by commercial growthManchester United have become the first sports team in the world to be valued at more than $3bn.A surge in the club's shares after a poor start when they were offered on the New York Stock Exchange in August has seen the overall value of United rise to $3.3bn (£2.1bn).According to Forbes, United are comfortably ahead of the world's second-most-valuable sports team, the NFL's Dallas Cowboys, worth $2.1bn (£1.4bn).The United shares were initially offered to the public at $14 and are now worth just under $17.It means a huge increase in the overall wealth of the Glazer family, who have a controlling interest in United, and the billionaire investor George Soros – the 22nd richest person in the world – who bought a 7.5% stake in the club.United's co...